/*-------------------------------------------------------------------------
 *
 * sha2.c
 *	   SHA-224、SHA-256、SHA-384 和 SHA-512 的 SHA 函数。
 *
 * 这包括 SHA2 加密哈希的后备实现。
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *	  src/common/sha2.c
 *
 *-------------------------------------------------------------------------
 */

/*	$OpenBSD: sha2.c,v 1.6 2004/05/03 02:57:36 millert Exp $	*/

/*
 * FILE:	sha2.c
 * AUTHOR:	Aaron D. Gifford <me@aarongifford.com>
 *
 * Copyright (c) 2000-2001, Aaron D. Gifford
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *	  notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *	  notice, this list of conditions and the following disclaimer in the
 *	  documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holder nor the names of contributors
 *	  may be used to endorse or promote products derived from this software
 *	  without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $From: sha2.c,v 1.1 2001/11/08 00:01:51 adg Exp adg $
 */


#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#include "sha2_int.h"

/*
 * 在后端，使用 palloc/pfree 来简化错误处理。在前端，
 * 使用 malloc 以便能够将失败状态返回给调用者。
 */
#ifndef FRONTEND
#define ALLOC(size) palloc(size)
#define FREE(ptr) pfree(ptr)
#else
#define ALLOC(size) malloc(size)
#define FREE(ptr) free(ptr)
#endif

/*
 * UNROLLED TRANSFORM LOOP 注释：
 * 你可以定义 SHA2_UNROLL_TRANSFORM 来使用展开的变换
 * 循环版本进行哈希变换轮（在此文件后续使用宏定义）。可以在命令行中定义，例如：
 *
 *	 cc -DSHA2_UNROLL_TRANSFORM -o sha2 sha2.c sha2prog.c
 *
 * 或在下面定义：
 *
 *	 #define SHA2_UNROLL_TRANSFORM
 *
 */

/*** SHA-256/384/512 各种长度定义 ***********************/
#define PG_SHA256_SHORT_BLOCK_LENGTH	(PG_SHA256_BLOCK_LENGTH - 8)
#define PG_SHA384_SHORT_BLOCK_LENGTH	(PG_SHA384_BLOCK_LENGTH - 16)
#define PG_SHA512_SHORT_BLOCK_LENGTH	(PG_SHA512_BLOCK_LENGTH - 16)

/*** 字节序反转宏 *******************************************/
#ifndef WORDS_BIGENDIAN
#define REVERSE32(w,x)	{ \
	uint32 fc_tmp = (w); \
	fc_tmp = (fc_tmp >> 16) | (fc_tmp << 16); \
	(x) = ((fc_tmp & 0xff00ff00UL) >> 8) | ((fc_tmp & 0x00ff00ffUL) << 8); \
}
#define REVERSE64(w,x)	{ \
	uint64 fc_tmp = (w); \
	fc_tmp = (fc_tmp >> 32) | (fc_tmp << 32); \
	fc_tmp = ((fc_tmp & 0xff00ff00ff00ff00ULL) >> 8) | \
		  ((fc_tmp & 0x00ff00ff00ff00ffULL) << 8); \
	(x) = ((fc_tmp & 0xffff0000ffff0000ULL) >> 16) | \
		  ((fc_tmp & 0x0000ffff0000ffffULL) << 16); \
}
#endif							/* 不是大端 */

/*
 * 增量添加无符号 64 位整数 n 到
 * 无符号 128 位整数（使用两个元素数组表示
 * 64 位字）：
 */
#define ADDINC128(w,n)	{ \
	(w)[0] += (uint64)(n); \
	if ((w)[0] < (n)) { \
		(w)[1]++; \
	} \
}

/*** 六个逻辑函数 ****************************************/
/*
 * 位移和旋转（由六个 SHA-XYZ 逻辑函数使用：
 *
 *	 注意：R 和 S 的命名在这里似乎是反向的（R 是位移，S 是旋转），
 *	 因为 SHA-256/384/512 描述文档
 *	 （见 http://www.iwar.org.uk/comsec/resources/cipher/sha256-384-512.pdf）
 *	 使用了同样的“反向”定义。
 */
/* 右移（在 SHA-256、SHA-384 和 SHA-512 中使用）： */
#define R(b,x)		((x) >> (b))
/* 32 位右旋转（在 SHA-256 中使用）： */
#define S32(b,x)	(((x) >> (b)) | ((x) << (32 - (b))))
/* 64 位右旋转（在 SHA-384 和 SHA-512 中使用）： */
#define S64(b,x)	(((x) >> (b)) | ((x) << (64 - (b))))

/* 在 SHA-256、SHA-384 和 SHA-512 中使用的六个逻辑函数中的两个： */
#define Ch(x,y,z)	(((x) & (y)) ^ ((~(x)) & (z)))
#define Maj(x,y,z)	(((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))

/* 在 SHA-256 中使用的六个逻辑函数中的四个： */
#define Sigma0_256(x)	(S32(2,  (x)) ^ S32(13, (x)) ^ S32(22, (x)))
#define Sigma1_256(x)	(S32(6,  (x)) ^ S32(11, (x)) ^ S32(25, (x)))
#define sigma0_256(x)	(S32(7,  (x)) ^ S32(18, (x)) ^ R(3 ,   (x)))
#define sigma1_256(x)	(S32(17, (x)) ^ S32(19, (x)) ^ R(10,   (x)))

/* 在 SHA-384 和 SHA-512 中使用的六个逻辑函数中的四个： */
#define Sigma0_512(x)	(S64(28, (x)) ^ S64(34, (x)) ^ S64(39, (x)))
#define Sigma1_512(x)	(S64(14, (x)) ^ S64(18, (x)) ^ S64(41, (x)))
#define sigma0_512(x)	(S64( 1, (x)) ^ S64( 8, (x)) ^ R( 7,   (x)))
#define sigma1_512(x)	(S64(19, (x)) ^ S64(61, (x)) ^ R( 6,   (x)))

/*** 内部函数原型 ***************************************/
/* 注意：这些不应直接从外部访问
 * 此库 -- 它们仅用于私有内部可见性/使用。
 */
static void fc_SHA512_Last(pg_sha512_ctx *fc_context);
static void fc_SHA256_Transform(pg_sha256_ctx *fc_context, const uint8 *fc_data);
static void fc_SHA512_Transform(pg_sha512_ctx *fc_context, const uint8 *fc_data);

/*** SHA-XYZ 初始哈希值和常量 ************************/
/* SHA-256 的哈希常量字 K： */
static const uint32 K256[64] = {
	0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL,
	0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
	0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
	0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
	0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
	0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
	0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL,
	0xc6e00bf3UL, 0xd5a79147UL, 0x06ca6351UL, 0x14292967UL,
	0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
	0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
	0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL,
	0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
	0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL,
	0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
	0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
	0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
};

/* SHA-224 的初始哈希值 H： */
static const uint32 sha224_initial_hash_value[8] = {
	0xc1059ed8UL,
	0x367cd507UL,
	0x3070dd17UL,
	0xf70e5939UL,
	0xffc00b31UL,
	0x68581511UL,
	0x64f98fa7UL,
	0xbefa4fa4UL
};

/* SHA-256 的初始哈希值 H： */
static const uint32 sha256_initial_hash_value[8] = {
	0x6a09e667UL,
	0xbb67ae85UL,
	0x3c6ef372UL,
	0xa54ff53aUL,
	0x510e527fUL,
	0x9b05688cUL,
	0x1f83d9abUL,
	0x5be0cd19UL
};

/* SHA-384 和 SHA-512 的哈希常量字 K： */
static const uint64 K512[80] = {
	0x428a2f98d728ae22ULL, 0x7137449123ef65cdULL,
	0xb5c0fbcfec4d3b2fULL, 0xe9b5dba58189dbbcULL,
	0x3956c25bf348b538ULL, 0x59f111f1b605d019ULL,
	0x923f82a4af194f9bULL, 0xab1c5ed5da6d8118ULL,
	0xd807aa98a3030242ULL, 0x12835b0145706fbeULL,
	0x243185be4ee4b28cULL, 0x550c7dc3d5ffb4e2ULL,
	0x72be5d74f27b896fULL, 0x80deb1fe3b1696b1ULL,
	0x9bdc06a725c71235ULL, 0xc19bf174cf692694ULL,
	0xe49b69c19ef14ad2ULL, 0xefbe4786384f25e3ULL,
	0x0fc19dc68b8cd5b5ULL, 0x240ca1cc77ac9c65ULL,
	0x2de92c6f592b0275ULL, 0x4a7484aa6ea6e483ULL,
	0x5cb0a9dcbd41fbd4ULL, 0x76f988da831153b5ULL,
	0x983e5152ee66dfabULL, 0xa831c66d2db43210ULL,
	0xb00327c898fb213fULL, 0xbf597fc7beef0ee4ULL,
	0xc6e00bf33da88fc2ULL, 0xd5a79147930aa725ULL,
	0x06ca6351e003826fULL, 0x142929670a0e6e70ULL,
	0x27b70a8546d22ffcULL, 0x2e1b21385c26c926ULL,
	0x4d2c6dfc5ac42aedULL, 0x53380d139d95b3dfULL,
	0x650a73548baf63deULL, 0x766a0abb3c77b2a8ULL,
	0x81c2c92e47edaee6ULL, 0x92722c851482353bULL,
	0xa2bfe8a14cf10364ULL, 0xa81a664bbc423001ULL,
	0xc24b8b70d0f89791ULL, 0xc76c51a30654be30ULL,
	0xd192e819d6ef5218ULL, 0xd69906245565a910ULL,
	0xf40e35855771202aULL, 0x106aa07032bbd1b8ULL,
	0x19a4c116b8d2d0c8ULL, 0x1e376c085141ab53ULL,
	0x2748774cdf8eeb99ULL, 0x34b0bcb5e19b48a8ULL,
	0x391c0cb3c5c95a63ULL, 0x4ed8aa4ae3418acbULL,
	0x5b9cca4f7763e373ULL, 0x682e6ff3d6b2b8a3ULL,
	0x748f82ee5defb2fcULL, 0x78a5636f43172f60ULL,
	0x84c87814a1f0ab72ULL, 0x8cc702081a6439ecULL,
	0x90befffa23631e28ULL, 0xa4506cebde82bde9ULL,
	0xbef9a3f7b2c67915ULL, 0xc67178f2e372532bULL,
	0xca273eceea26619cULL, 0xd186b8c721c0c207ULL,
	0xeada7dd6cde0eb1eULL, 0xf57d4f7fee6ed178ULL,
	0x06f067aa72176fbaULL, 0x0a637dc5a2c898a6ULL,
	0x113f9804bef90daeULL, 0x1b710b35131c471bULL,
	0x28db77f523047d84ULL, 0x32caab7b40c72493ULL,
	0x3c9ebe0a15c9bebcULL, 0x431d67c49c100d4cULL,
	0x4cc5d4becb3e42b6ULL, 0x597f299cfc657e2aULL,
	0x5fcb6fab3ad6faecULL, 0x6c44198c4a475817ULL
};

/* SHA-384 的初始哈希值 H */
static const uint64 sha384_initial_hash_value[8] = {
	0xcbbb9d5dc1059ed8ULL,
	0x629a292a367cd507ULL,
	0x9159015a3070dd17ULL,
	0x152fecd8f70e5939ULL,
	0x67332667ffc00b31ULL,
	0x8eb44a8768581511ULL,
	0xdb0c2e0d64f98fa7ULL,
	0x47b5481dbefa4fa4ULL
};

/* SHA-512 的初始哈希值 H */
static const uint64 sha512_initial_hash_value[8] = {
	0x6a09e667f3bcc908ULL,
	0xbb67ae8584caa73bULL,
	0x3c6ef372fe94f82bULL,
	0xa54ff53a5f1d36f1ULL,
	0x510e527fade682d1ULL,
	0x9b05688c2b3e6c1fULL,
	0x1f83d9abfb41bd6bULL,
	0x5be0cd19137e2179ULL
};


/*** SHA-256: *********************************************************/
void pg_sha256_init(pg_sha256_ctx *fc_context)
{
	if (fc_context == NULL)
		return;
	memcpy(fc_context->state, sha256_initial_hash_value, PG_SHA256_DIGEST_LENGTH);
	memset(fc_context->buffer, 0, PG_SHA256_BLOCK_LENGTH);
	fc_context->bitcount = 0;
}

#ifdef SHA2_UNROLL_TRANSFORM

/* 展开的 SHA-256 轮宏： */

#define ROUND256_0_TO_15(a,b,c,d,e,f,g,h) do {					\
	W256[j] = (uint32)data[3] | ((uint32)data[2] << 8) |		\
		((uint32)data[1] << 16) | ((uint32)data[0] << 24);		\
	data += 4;								\
	T1 = (h) + Sigma1_256((e)) + Ch((e), (f), (g)) + K256[j] + W256[j]; \
	(d) += T1;								\
	(h) = T1 + Sigma0_256((a)) + Maj((a), (b), (c));			\
	j++;									\
} while(0)

#define ROUND256(a,b,c,d,e,f,g,h) do {						\
	s0 = W256[(j+1)&0x0f];							\
	s0 = sigma0_256(s0);							\
	s1 = W256[(j+14)&0x0f];							\
	s1 = sigma1_256(s1);							\
	T1 = (h) + Sigma1_256((e)) + Ch((e), (f), (g)) + K256[j] +		\
		 (W256[j&0x0f] += s1 + W256[(j+9)&0x0f] + s0);			\
	(d) += T1;								\
	(h) = T1 + Sigma0_256((a)) + Maj((a), (b), (c));			\
	j++;									\
} while(0)

static void SHA256_Transform(pg_sha256_ctx *context, const uint8 *data)
{
	uint32		a,
				b,
				c,
				d,
				e,
				f,
				g,
				h,
				s0,
				s1;
	uint32		T1,
			   *W256;
	int			j;

	W256 = (uint32 *) context->buffer;

	/* 用上一个中间值初始化寄存器 */
	a = context->state[0];
	b = context->state[1];
	c = context->state[2];
	d = context->state[3];
	e = context->state[4];
	f = context->state[5];
	g = context->state[6];
	h = context->state[7];

	j = 0;
	do
	{
		/* 轮 0 到 15（展开）： */
		ROUND256_0_TO_15(a, b, c, d, e, f, g, h);
		ROUND256_0_TO_15(h, a, b, c, d, e, f, g);
		ROUND256_0_TO_15(g, h, a, b, c, d, e, f);
		ROUND256_0_TO_15(f, g, h, a, b, c, d, e);
		ROUND256_0_TO_15(e, f, g, h, a, b, c, d);
		ROUND256_0_TO_15(d, e, f, g, h, a, b, c);
		ROUND256_0_TO_15(c, d, e, f, g, h, a, b);
		ROUND256_0_TO_15(b, c, d, e, f, g, h, a);
	} while (j < 16);

	/* 现在进行剩余轮到 64： */
	do
	{
		ROUND256(a, b, c, d, e, f, g, h);
		ROUND256(h, a, b, c, d, e, f, g);
		ROUND256(g, h, a, b, c, d, e, f);
		ROUND256(f, g, h, a, b, c, d, e);
		ROUND256(e, f, g, h, a, b, c, d);
		ROUND256(d, e, f, g, h, a, b, c);
		ROUND256(c, d, e, f, g, h, a, b);
		ROUND256(b, c, d, e, f, g, h, a);
	} while (j < 64);

	/* 计算当前中间哈希值 */
	context->state[0] += a;
	context->state[1] += b;
	context->state[2] += c;
	context->state[3] += d;
	context->state[4] += e;
	context->state[5] += f;
	context->state[6] += g;
	context->state[7] += h;

	/* 清理 */
	a = b = c = d = e = f = g = h = T1 = 0;
}
#else							/* SHA2_UNROLL_TRANSFORM */

static void fc_SHA256_Transform(pg_sha256_ctx *fc_context, const uint8 *fc_data)
{
	uint32		fc_a,
				fc_b,
				fc_c,
				fc_d,
				fc_e,
				fc_f,
				fc_g,
				fc_h,
				fc_s0,
				fc_s1;
	uint32		fc_T1,
				fc_T2,
			   *fc_W256;
	int			fc_j;

	fc_W256 = (uint32 *) fc_context->buffer;

	/* 用上一个中间值初始化寄存器 */
	fc_a = fc_context->state[0];
	fc_b = fc_context->state[1];
	fc_c = fc_context->state[2];
	fc_d = fc_context->state[3];
	fc_e = fc_context->state[4];
	fc_f = fc_context->state[5];
	fc_g = fc_context->state[6];
	fc_h = fc_context->state[7];

	fc_j = 0;
	do
	{
		fc_W256[fc_j] = (uint32) fc_data[3] | ((uint32) fc_data[2] << 8) |
			((uint32) fc_data[1] << 16) | ((uint32) fc_data[0] << 24);
		fc_data += 4;
		/* 应用 SHA-256 压缩函数以更新 a..h */
		fc_T1 = fc_h + Sigma1_256(fc_e) + Ch(fc_e, fc_f, fc_g) + K256[fc_j] + fc_W256[fc_j];
		fc_T2 = Sigma0_256(fc_a) + Maj(fc_a, fc_b, fc_c);
		fc_h = fc_g;
		fc_g = fc_f;
		fc_f = fc_e;
		fc_e = fc_d + fc_T1;
		fc_d = fc_c;
		fc_c = fc_b;
		fc_b = fc_a;
		fc_a = fc_T1 + fc_T2;

		fc_j++;
	} while (fc_j < 16);

	do
	{
		/* 消息块扩展的一部分： */
		fc_s0 = fc_W256[(fc_j + 1) & 0x0f];
		fc_s0 = sigma0_256(fc_s0);
		fc_s1 = fc_W256[(fc_j + 14) & 0x0f];
		fc_s1 = sigma1_256(fc_s1);

		/* 应用 SHA-256 压缩函数以更新 a..h */
		fc_T1 = fc_h + Sigma1_256(fc_e) + Ch(fc_e, fc_f, fc_g) + K256[fc_j] +
			(fc_W256[fc_j & 0x0f] += fc_s1 + fc_W256[(fc_j + 9) & 0x0f] + fc_s0);
		fc_T2 = Sigma0_256(fc_a) + Maj(fc_a, fc_b, fc_c);
		fc_h = fc_g;
		fc_g = fc_f;
		fc_f = fc_e;
		fc_e = fc_d + fc_T1;
		fc_d = fc_c;
		fc_c = fc_b;
		fc_b = fc_a;
		fc_a = fc_T1 + fc_T2;

		fc_j++;
	} while (fc_j < 64);

	/* 计算当前中间哈希值 */
	fc_context->state[0] += fc_a;
	fc_context->state[1] += fc_b;
	fc_context->state[2] += fc_c;
	fc_context->state[3] += fc_d;
	fc_context->state[4] += fc_e;
	fc_context->state[5] += fc_f;
	fc_context->state[6] += fc_g;
	fc_context->state[7] += fc_h;

	/* 清理 */
	fc_a = fc_b = fc_c = fc_d = fc_e = fc_f = fc_g = fc_h = fc_T1 = fc_T2 = 0;
}
#endif							/* SHA2_UNROLL_TRANSFORM */

void pg_sha256_update(pg_sha256_ctx *fc_context, const uint8 *fc_data, size_t fc_len)
{
	size_t		fc_freespace,
				fc_usedspace;

	/* 调用时没有数据是有效的（我们什么都不做） */
	if (fc_len == 0)
		return;

	fc_usedspace = (fc_context->bitcount >> 3) % PG_SHA256_BLOCK_LENGTH;
	if (fc_usedspace > 0)
	{
		/* 计算缓冲区中可用的空闲空间大小 */
		fc_freespace = PG_SHA256_BLOCK_LENGTH - fc_usedspace;

		if (fc_len >= fc_freespace)
		{
			/* 完全填充缓冲区并处理它 */
			memcpy(&fc_context->buffer[fc_usedspace], fc_data, fc_freespace);
			fc_context->bitcount += fc_freespace << 3;
			fc_len -= fc_freespace;
			fc_data += fc_freespace;
			fc_SHA256_Transform(fc_context, fc_context->buffer);
		}
		else
		{
			/* 缓冲区尚未满 */
			memcpy(&fc_context->buffer[fc_usedspace], fc_data, fc_len);
			fc_context->bitcount += fc_len << 3;
			/* 清理: */
			fc_usedspace = fc_freespace = 0;
			return;
		}
	}
	while (fc_len >= PG_SHA256_BLOCK_LENGTH)
	{
		/* 尽可能处理完整的块 */
		fc_SHA256_Transform(fc_context, fc_data);
		fc_context->bitcount += PG_SHA256_BLOCK_LENGTH << 3;
		fc_len -= PG_SHA256_BLOCK_LENGTH;
		fc_data += PG_SHA256_BLOCK_LENGTH;
	}
	if (fc_len > 0)
	{
		/* 还有剩余，所以保存它们 */
		memcpy(fc_context->buffer, fc_data, fc_len);
		fc_context->bitcount += fc_len << 3;
	}
	/* 清理: */
	fc_usedspace = fc_freespace = 0;
}

static void fc_SHA256_Last(pg_sha256_ctx *fc_context)
{
	unsigned int fc_usedspace;

	fc_usedspace = (fc_context->bitcount >> 3) % PG_SHA256_BLOCK_LENGTH;
#ifndef WORDS_BIGENDIAN
	/* 从主机字节顺序转换 */
	REVERSE64(fc_context->bitcount, fc_context->bitcount);
#endif
	if (fc_usedspace > 0)
	{
		/* 开始用1位进行填充: */
		fc_context->buffer[fc_usedspace++] = 0x80;

		if (fc_usedspace <= PG_SHA256_SHORT_BLOCK_LENGTH)
		{
			/* 为最后一次变换做准备: */
			memset(&fc_context->buffer[fc_usedspace], 0, PG_SHA256_SHORT_BLOCK_LENGTH - fc_usedspace);
		}
		else
		{
			if (fc_usedspace < PG_SHA256_BLOCK_LENGTH)
			{
				memset(&fc_context->buffer[fc_usedspace], 0, PG_SHA256_BLOCK_LENGTH - fc_usedspace);
			}
			/* 进行倒数第二次变换: */
			fc_SHA256_Transform(fc_context, fc_context->buffer);

			/* 并为最后一次变换做准备: */
			memset(fc_context->buffer, 0, PG_SHA256_SHORT_BLOCK_LENGTH);
		}
	}
	else
	{
		/* 为最后一次变换做准备: */
		memset(fc_context->buffer, 0, PG_SHA256_SHORT_BLOCK_LENGTH);

		/* 开始用1位进行填充: */
		*fc_context->buffer = 0x80;
	}
	/* 设置位计数: */
	*(uint64 *) &fc_context->buffer[PG_SHA256_SHORT_BLOCK_LENGTH] = fc_context->bitcount;

	/* 最终变换: */
	fc_SHA256_Transform(fc_context, fc_context->buffer);
}

void pg_sha256_final(pg_sha256_ctx *fc_context, uint8 *fc_digest)
{
	/* 如果没有传递摘要缓冲区，我们就不去做这个: */
	if (fc_digest != NULL)
	{
		fc_SHA256_Last(fc_context);

#ifndef WORDS_BIGENDIAN
		{
			/* 转换为主机字节顺序 */
			int			fc_j;

			for (fc_j = 0; fc_j < 8; fc_j++)
			{
				REVERSE32(fc_context->state[fc_j], fc_context->state[fc_j]);
			}
		}
#endif
		memcpy(fc_digest, fc_context->state, PG_SHA256_DIGEST_LENGTH);
	}

	/* 清理状态数据: */
	memset(fc_context, 0, sizeof(pg_sha256_ctx));
}


/*** SHA-512: *********************************************************/
void pg_sha512_init(pg_sha512_ctx *fc_context)
{
	if (fc_context == NULL)
		return;
	memcpy(fc_context->state, sha512_initial_hash_value, PG_SHA512_DIGEST_LENGTH);
	memset(fc_context->buffer, 0, PG_SHA512_BLOCK_LENGTH);
	fc_context->bitcount[0] = fc_context->bitcount[1] = 0;
}

#ifdef SHA2_UNROLL_TRANSFORM

/* 展开SHA-512轮宏: */

#define ROUND512_0_TO_15(a,b,c,d,e,f,g,h) do {					\
	W512[j] = (uint64)data[7] | ((uint64)data[6] << 8) |		\
		((uint64)data[5] << 16) | ((uint64)data[4] << 24) |		\
		((uint64)data[3] << 32) | ((uint64)data[2] << 40) |		\
		((uint64)data[1] << 48) | ((uint64)data[0] << 56);		\
	data += 8;								\
	T1 = (h) + Sigma1_512((e)) + Ch((e), (f), (g)) + K512[j] + W512[j]; \
	(d) += T1;								\
	(h) = T1 + Sigma0_512((a)) + Maj((a), (b), (c));			\
	j++;									\
} while(0)


#define ROUND512(a,b,c,d,e,f,g,h) do {						\
	s0 = W512[(j+1)&0x0f];							\
	s0 = sigma0_512(s0);							\
	s1 = W512[(j+14)&0x0f];							\
	s1 = sigma1_512(s1);							\
	T1 = (h) + Sigma1_512((e)) + Ch((e), (f), (g)) + K512[j] +		\
			 (W512[j&0x0f] += s1 + W512[(j+9)&0x0f] + s0);			\
	(d) += T1;								\
	(h) = T1 + Sigma0_512((a)) + Maj((a), (b), (c));			\
	j++;									\
} while(0)

static void SHA512_Transform(pg_sha512_ctx *context, const uint8 *data)
{
	uint64		a,
				b,
				c,
				d,
				e,
				f,
				g,
				h,
				s0,
				s1;
	uint64		T1,
			   *W512 = (uint64 *) context->buffer;
	int			j;

	/* 用上一个中间值初始化寄存器 */
	a = context->state[0];
	b = context->state[1];
	c = context->state[2];
	d = context->state[3];
	e = context->state[4];
	f = context->state[5];
	g = context->state[6];
	h = context->state[7];

	j = 0;
	do
	{
		ROUND512_0_TO_15(a, b, c, d, e, f, g, h);
		ROUND512_0_TO_15(h, a, b, c, d, e, f, g);
		ROUND512_0_TO_15(g, h, a, b, c, d, e, f);
		ROUND512_0_TO_15(f, g, h, a, b, c, d, e);
		ROUND512_0_TO_15(e, f, g, h, a, b, c, d);
		ROUND512_0_TO_15(d, e, f, g, h, a, b, c);
		ROUND512_0_TO_15(c, d, e, f, g, h, a, b);
		ROUND512_0_TO_15(b, c, d, e, f, g, h, a);
	} while (j < 16);

	/* 现在进行剩余的轮数，直到79: */
	do
	{
		ROUND512(a, b, c, d, e, f, g, h);
		ROUND512(h, a, b, c, d, e, f, g);
		ROUND512(g, h, a, b, c, d, e, f);
		ROUND512(f, g, h, a, b, c, d, e);
		ROUND512(e, f, g, h, a, b, c, d);
		ROUND512(d, e, f, g, h, a, b, c);
		ROUND512(c, d, e, f, g, h, a, b);
		ROUND512(b, c, d, e, f, g, h, a);
	} while (j < 80);

	/* 计算当前中间哈希值 */
	context->state[0] += a;
	context->state[1] += b;
	context->state[2] += c;
	context->state[3] += d;
	context->state[4] += e;
	context->state[5] += f;
	context->state[6] += g;
	context->state[7] += h;

	/* 清理 */
	a = b = c = d = e = f = g = h = T1 = 0;
}
#else							/* SHA2_UNROLL_TRANSFORM */

static void fc_SHA512_Transform(pg_sha512_ctx *fc_context, const uint8 *fc_data)
{
	uint64		fc_a,
				fc_b,
				fc_c,
				fc_d,
				fc_e,
				fc_f,
				fc_g,
				fc_h,
				fc_s0,
				fc_s1;
	uint64		fc_T1,
				fc_T2,
			   *fc_W512 = (uint64 *) fc_context->buffer;
	int			fc_j;

	/* 用上一个中间值初始化寄存器 */
	fc_a = fc_context->state[0];
	fc_b = fc_context->state[1];
	fc_c = fc_context->state[2];
	fc_d = fc_context->state[3];
	fc_e = fc_context->state[4];
	fc_f = fc_context->state[5];
	fc_g = fc_context->state[6];
	fc_h = fc_context->state[7];

	fc_j = 0;
	do
	{
		fc_W512[fc_j] = (uint64) fc_data[7] | ((uint64) fc_data[6] << 8) |
			((uint64) fc_data[5] << 16) | ((uint64) fc_data[4] << 24) |
			((uint64) fc_data[3] << 32) | ((uint64) fc_data[2] << 40) |
			((uint64) fc_data[1] << 48) | ((uint64) fc_data[0] << 56);
		fc_data += 8;
		/* 应用SHA-512压缩函数更新a..h */
		fc_T1 = fc_h + Sigma1_512(fc_e) + Ch(fc_e, fc_f, fc_g) + K512[fc_j] + fc_W512[fc_j];
		fc_T2 = Sigma0_512(fc_a) + Maj(fc_a, fc_b, fc_c);
		fc_h = fc_g;
		fc_g = fc_f;
		fc_f = fc_e;
		fc_e = fc_d + fc_T1;
		fc_d = fc_c;
		fc_c = fc_b;
		fc_b = fc_a;
		fc_a = fc_T1 + fc_T2;

		fc_j++;
	} while (fc_j < 16);

	do
	{
		/* 消息块扩展的一部分： */
		fc_s0 = fc_W512[(fc_j + 1) & 0x0f];
		fc_s0 = sigma0_512(fc_s0);
		fc_s1 = fc_W512[(fc_j + 14) & 0x0f];
		fc_s1 = sigma1_512(fc_s1);

		/* 应用SHA-512压缩函数更新a..h */
		fc_T1 = fc_h + Sigma1_512(fc_e) + Ch(fc_e, fc_f, fc_g) + K512[fc_j] +
			(fc_W512[fc_j & 0x0f] += fc_s1 + fc_W512[(fc_j + 9) & 0x0f] + fc_s0);
		fc_T2 = Sigma0_512(fc_a) + Maj(fc_a, fc_b, fc_c);
		fc_h = fc_g;
		fc_g = fc_f;
		fc_f = fc_e;
		fc_e = fc_d + fc_T1;
		fc_d = fc_c;
		fc_c = fc_b;
		fc_b = fc_a;
		fc_a = fc_T1 + fc_T2;

		fc_j++;
	} while (fc_j < 80);

	/* 计算当前中间哈希值 */
	fc_context->state[0] += fc_a;
	fc_context->state[1] += fc_b;
	fc_context->state[2] += fc_c;
	fc_context->state[3] += fc_d;
	fc_context->state[4] += fc_e;
	fc_context->state[5] += fc_f;
	fc_context->state[6] += fc_g;
	fc_context->state[7] += fc_h;

	/* 清理 */
	fc_a = fc_b = fc_c = fc_d = fc_e = fc_f = fc_g = fc_h = fc_T1 = fc_T2 = 0;
}
#endif							/* SHA2_UNROLL_TRANSFORM */

void pg_sha512_update(pg_sha512_ctx *fc_context, const uint8 *fc_data, size_t fc_len)
{
	size_t		fc_freespace,
				fc_usedspace;

	/* 调用时没有数据是有效的（我们什么都不做） */
	if (fc_len == 0)
		return;

	fc_usedspace = (fc_context->bitcount[0] >> 3) % PG_SHA512_BLOCK_LENGTH;
	if (fc_usedspace > 0)
	{
		/* 计算缓冲区中可用的空闲空间大小 */
		fc_freespace = PG_SHA512_BLOCK_LENGTH - fc_usedspace;

		if (fc_len >= fc_freespace)
		{
			/* 完全填充缓冲区并处理它 */
			memcpy(&fc_context->buffer[fc_usedspace], fc_data, fc_freespace);
			ADDINC128(fc_context->bitcount, fc_freespace << 3);
			fc_len -= fc_freespace;
			fc_data += fc_freespace;
			fc_SHA512_Transform(fc_context, fc_context->buffer);
		}
		else
		{
			/* 缓冲区尚未满 */
			memcpy(&fc_context->buffer[fc_usedspace], fc_data, fc_len);
			ADDINC128(fc_context->bitcount, fc_len << 3);
			/* 清理: */
			fc_usedspace = fc_freespace = 0;
			return;
		}
	}
	while (fc_len >= PG_SHA512_BLOCK_LENGTH)
	{
		/* 尽可能处理完整的块 */
		fc_SHA512_Transform(fc_context, fc_data);
		ADDINC128(fc_context->bitcount, PG_SHA512_BLOCK_LENGTH << 3);
		fc_len -= PG_SHA512_BLOCK_LENGTH;
		fc_data += PG_SHA512_BLOCK_LENGTH;
	}
	if (fc_len > 0)
	{
		/* 还有剩余，所以保存它们 */
		memcpy(fc_context->buffer, fc_data, fc_len);
		ADDINC128(fc_context->bitcount, fc_len << 3);
	}
	/* 清理: */
	fc_usedspace = fc_freespace = 0;
}

static void fc_SHA512_Last(pg_sha512_ctx *fc_context)
{
	unsigned int fc_usedspace;

	fc_usedspace = (fc_context->bitcount[0] >> 3) % PG_SHA512_BLOCK_LENGTH;
#ifndef WORDS_BIGENDIAN
	/* 从主机字节顺序转换 */
	REVERSE64(fc_context->bitcount[0], fc_context->bitcount[0]);
	REVERSE64(fc_context->bitcount[1], fc_context->bitcount[1]);
#endif
	if (fc_usedspace > 0)
	{
		/* 开始用1位进行填充: */
		fc_context->buffer[fc_usedspace++] = 0x80;

		if (fc_usedspace <= PG_SHA512_SHORT_BLOCK_LENGTH)
		{
			/* 为最后一次变换做准备: */
			memset(&fc_context->buffer[fc_usedspace], 0, PG_SHA512_SHORT_BLOCK_LENGTH - fc_usedspace);
		}
		else
		{
			if (fc_usedspace < PG_SHA512_BLOCK_LENGTH)
			{
				memset(&fc_context->buffer[fc_usedspace], 0, PG_SHA512_BLOCK_LENGTH - fc_usedspace);
			}
			/* 进行倒数第二次变换: */
			fc_SHA512_Transform(fc_context, fc_context->buffer);

			/* 并为最后一次变换做准备: */
			memset(fc_context->buffer, 0, PG_SHA512_BLOCK_LENGTH - 2);
		}
	}
	else
	{
		/* 准备最终变换: */
		memset(fc_context->buffer, 0, PG_SHA512_SHORT_BLOCK_LENGTH);

		/* 开始用1位进行填充: */
		*fc_context->buffer = 0x80;
	}
	/* 存储输入数据的长度（以位为单位）: */
	*(uint64 *) &fc_context->buffer[PG_SHA512_SHORT_BLOCK_LENGTH] = fc_context->bitcount[1];
	*(uint64 *) &fc_context->buffer[PG_SHA512_SHORT_BLOCK_LENGTH + 8] = fc_context->bitcount[0];

	/* 最终变换: */
	fc_SHA512_Transform(fc_context, fc_context->buffer);
}

void pg_sha512_final(pg_sha512_ctx *fc_context, uint8 *fc_digest)
{
	/* 如果没有传递摘要缓冲区，我们就不去做这个: */
	if (fc_digest != NULL)
	{
		fc_SHA512_Last(fc_context);

		/* 保存哈希数据以供输出: */
#ifndef WORDS_BIGENDIAN
		{
			/* 转换为主机字节顺序 */
			int			fc_j;

			for (fc_j = 0; fc_j < 8; fc_j++)
			{
				REVERSE64(fc_context->state[fc_j], fc_context->state[fc_j]);
			}
		}
#endif
		memcpy(fc_digest, fc_context->state, PG_SHA512_DIGEST_LENGTH);
	}

	/* 清零状态数据 */
	memset(fc_context, 0, sizeof(pg_sha512_ctx));
}


/*** SHA-384: *********************************************************/
void pg_sha384_init(pg_sha384_ctx *fc_context)
{
	if (fc_context == NULL)
		return;
	memcpy(fc_context->state, sha384_initial_hash_value, PG_SHA512_DIGEST_LENGTH);
	memset(fc_context->buffer, 0, PG_SHA384_BLOCK_LENGTH);
	fc_context->bitcount[0] = fc_context->bitcount[1] = 0;
}

void pg_sha384_update(pg_sha384_ctx *fc_context, const uint8 *fc_data, size_t fc_len)
{
	pg_sha512_update((pg_sha512_ctx *) fc_context, fc_data, fc_len);
}

void pg_sha384_final(pg_sha384_ctx *fc_context, uint8 *fc_digest)
{
	/* 如果没有传递摘要缓冲区，我们就不去做这个: */
	if (fc_digest != NULL)
	{
		fc_SHA512_Last((pg_sha512_ctx *) fc_context);

		/* 保存哈希数据以供输出: */
#ifndef WORDS_BIGENDIAN
		{
			/* 转换为主机字节顺序 */
			int			fc_j;

			for (fc_j = 0; fc_j < 6; fc_j++)
			{
				REVERSE64(fc_context->state[fc_j], fc_context->state[fc_j]);
			}
		}
#endif
		memcpy(fc_digest, fc_context->state, PG_SHA384_DIGEST_LENGTH);
	}

	/* 清零状态数据 */
	memset(fc_context, 0, sizeof(pg_sha384_ctx));
}

/*** SHA-224: *********************************************************/
void pg_sha224_init(pg_sha224_ctx *fc_context)
{
	if (fc_context == NULL)
		return;
	memcpy(fc_context->state, sha224_initial_hash_value, PG_SHA256_DIGEST_LENGTH);
	memset(fc_context->buffer, 0, PG_SHA256_BLOCK_LENGTH);
	fc_context->bitcount = 0;
}

void pg_sha224_update(pg_sha224_ctx *fc_context, const uint8 *fc_data, size_t fc_len)
{
	pg_sha256_update((pg_sha256_ctx *) fc_context, fc_data, fc_len);
}

void pg_sha224_final(pg_sha224_ctx *fc_context, uint8 *fc_digest)
{
	/* 如果没有传递摘要缓冲区，我们就不去做这个: */
	if (fc_digest != NULL)
	{
		fc_SHA256_Last(fc_context);

#ifndef WORDS_BIGENDIAN
		{
			/* 转换为主机字节顺序 */
			int			fc_j;

			for (fc_j = 0; fc_j < 8; fc_j++)
			{
				REVERSE32(fc_context->state[fc_j], fc_context->state[fc_j]);
			}
		}
#endif
		memcpy(fc_digest, fc_context->state, PG_SHA224_DIGEST_LENGTH);
	}

	/* 清理状态数据: */
	memset(fc_context, 0, sizeof(pg_sha224_ctx));
}
